In data storage systems, data is stored on a storage medium. The storage medium may be a polymer film. In various embodiments of the invention, the storage medium may be one of a magnetic film, a ferro-electric film, and a phase-change film. In thermo-mechanical data storage, data is stored in the form of a plurality of topographical features on the storage medium. The data is written on the storage medium by using a transducer integrated in a tip of a cantilever structure. The transducer includes a heating element that creates the plurality of topographical features to store data. Data stored on the storage medium is read by scanning the storage medium with the tip of the cantilever structure. The tip co-operates with the plurality of topographical features to read the data.
In data storage systems that read data by sensing the topographic state of a surface, the temperature dependence properties of silicon are used to sense changes in separation of cantilever structure and substrate. A read-heater is integrated in a cantilever structure. While scanning the storage medium for reading the data, if the tip of the cantilever structure moves into a topographical feature, the read head integrated in the cantilever structure moves closer to the substrate. As a result of this, the efficiency of cooling of the read-heater increases. The increase in efficiency of cooling results in a decrease in temperature. The decrease in temperature is sensed as change in resistance of the read-heater. The change in resistance of the read-heater is represented as data.
U.S. Pat. No. 6,515,957, titled “Ferroelectric drive for data storage” assigned to International Business Machines Corporation, Armonk, N.Y., discloses a data storage system that preferably comprises an electrically conducting rotatable hard disk substrate having a ferroelectric storage layer that comprises storage cells which can be written and read along concentric recording tracks, a pivoted servo arm with a free end for movement across the recording tracks. The free end of the servo arm includes both a write head, including an electrically conducting tip, and a read head, including a field effect transistor (FET), held close to the disk surface. The FET has a gate electrode and is positioned on the servo arm with the gate electrode held close to the ferroelectric surface of the disk during read operations of the data storage system. Read and write operations can be performed with standard semiconductor technologies in combination with existing magnetic hard-disk servo-control architecture.
Additionally, U.S. Pat. No. 6,477,132, titled, “Probe and information recording/reproduction apparatus using the same” assigned to Canon Kabushiki Kaisha, Tokyo, JP, discloses a probe including a cantilever having a movable end and formed from an elastic body, an electroconductive sensing needle arranged at the movable end of the cantilever, and a FET arranged at the movable end of the cantilever and having a gate electrode electronically connected to the electroconductive sensing needle. The probe may further comprise another FET formed on the cantilever and having its drain electrically connected to the sensing needle. The probe may be used in an information recording/reproduction apparatus.
However, each of these prior art suffers from one or more of the following limitations. Speed of read-back is limited by heat capacity of the read-heater and heat sinking of the read-heater. Additionally, minimum volume of a read-heater is limited due to noise considerations. The cantilever structures are mechanically weak and have a limited mechanical speed because they require thermal isolation. Further, the signal to carrier ratio is small, which complicates the design of detection electronics. The tip of cantilever structure is used for electric writing and not for creating or moving into/over a topographical feature. Further, the tip is not used to sense distance between the cantilever structure and the substrate.